M580 Safety use of Analog Inputs (BMXSAI0410)

[MatthewM]

Hi everyone,

Has anyone out there used analogue inputs in safety applications?  We have a BMXSAI0410.  There are no functions available in safety code for scaling from raw to EU.  Do we just get used to the idea of working in raw only, or do we scale it manually with half a dozen math blocks?

Thanks

[Hennie_Smith]

Hi. The SAFE sections should be used only for the safety logic based on the Cause&Effect matrix compiled during the Risk assessment. (Comparisons will need to be with the RAW values). To scale the values for HMI/SCADA purposes you can read the values via the interface in the PROCESS sections and scale it accordingly.

[MatthewM]

Thanks for the reply.  Yes I am already scaling in the Process section for SCADA, but I do find it odd that it is expected to use RAW in the safety application.  I thought the days of having to use RAW died with 984.  Apparently not.

Cheers.

[Farzad_Samimi · Accepted solution]

Hi Matthew,

There is a demo project for M580s when you install Control Expert, there is a DFB create for safety section that scales the analog input.

[MatthewM]

Thanks for that.  I had not found that demo app.  I will mark this as a solution, even though I requires making a DFB (using system Safety Functions).  The client site does not want is to create DFBs for safety, so I will either have to replicate the contents of the DFB for each analog (only 2), or just live with using RAW.